Known boat-supporting rollers use a solid plastic sleeve insert or a steel sleeve insert around the roller shaft to reduce rolling friction. Known solid plastic inserts will melt and deform when forced into the interior diameter of a hot rubber roller which supports the boat.
The patent to Miller, U.S. Pat. No. 2,660,443, shows a boat keel supporting roller having a metal shaft surrounded by a sleeve and a roll each of which fits closely adjacent to the other. The Baron patent, U.S. Pat. No. 2,887,203, shows rollers each having a tubular resilient rubber sleeve coated with graphite to minimize frictional resistance when the roller is rotated on the inner sleeve. The sleeve may be a metallic, helically wound hose, and the interior of the sleeve is fitted with a plurality of resilient rods which may be galvanized spring steel.
The patent to Trumbull, U.S. Pat. No. 3,056,517, describes a boat trailer having boat supporting rollers in which each rubber roller is bonded to a central metal rod or shaft. The Kummerl patent, U.S. Pat. No. 4,299,022, describes a transport drum used for processing photographic film or paper. The apparatus includes an insert having a plurality of longitudinally extending ridges over which a cylindrical foam covering fits closely. The foam material is secured directly to the insert and ridges without any air channels therebetween.